EP1760497A2 - Optisches Teil und projektionsähnliche Anzeigevorrichtung damit - Google Patents

Optisches Teil und projektionsähnliche Anzeigevorrichtung damit Download PDF

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Publication number
EP1760497A2
EP1760497A2 EP20060017835 EP06017835A EP1760497A2 EP 1760497 A2 EP1760497 A2 EP 1760497A2 EP 20060017835 EP20060017835 EP 20060017835 EP 06017835 A EP06017835 A EP 06017835A EP 1760497 A2 EP1760497 A2 EP 1760497A2
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EP
European Patent Office
Prior art keywords
membrane
compound
light
reflecting
reflecting membrane
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP20060017835
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English (en)
French (fr)
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EP1760497A3 (de
EP1760497B1 (de
Inventor
Hiroshi Sasaki
Makiko Sugibayashi
Sadayuki Nishimura
Kiyomi Nakamura
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Maxell Ltd
Original Assignee
Hitachi Ltd
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Filing date
Publication date
Priority claimed from JP2005254303A external-priority patent/JP4760237B2/ja
Priority claimed from JP2006089836A external-priority patent/JP4811081B2/ja
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Publication of EP1760497A2 publication Critical patent/EP1760497A2/de
Publication of EP1760497A3 publication Critical patent/EP1760497A3/de
Application granted granted Critical
Publication of EP1760497B1 publication Critical patent/EP1760497B1/de
Expired - Fee Related legal-status Critical Current
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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/111—Anti-reflection coatings using layers comprising organic materials
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2033—LED or laser light sources
    • G03B21/204—LED or laser light sources using secondary light emission, e.g. luminescence or fluorescence
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2073—Polarisers in the lamp house
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/28—Reflectors in projection beam
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
    • H04N9/3105—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3167—Modulator illumination systems for polarizing the light beam
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133502—Antiglare, refractive index matching layers

Definitions

  • the present invention relates to a lens provided with an anti-reflecting membrane, and a projection type display apparatus using the same.
  • Anti-reflecting membranes are formed on the light receiving face and the light outgoing face of lenses used for cameras or telescopes because loss of light occurs due to reflection caused by difference in refractive index at the interface with air, and reflection of ambient objects on the lens surface is large in an environment of strong outer light.
  • Liquid crystal projectors and rear projection type liquid crystal projection televisions begin to spread in companies and general households as projection type display apparatuses which use as a light source a super high pressure mercury lamp performing irradiation of a large volume of light and which display projected images on a screen through a display device such as a liquid crystal display device.
  • the light emitted from a lamp as a light source passes through a plurality of lenses, a polarization converter, a dichroic mirror, a display device and the like, and is synthesized by a dichroic cross-prism, and displayed on a screen through a projection lens.
  • the image light outputted from the projection lens is corrected in its direction by a rear mirror and projected on a screen to display an image.
  • a light travels through various optical parts, and hence if reflection at the light receiving face and light outgoing face is great, spectral volume becomes smaller, and, as a result, the image becomes darker. Therefore, anti-reflecting membranes are provided on the light receiving face and the light emitting face of the respective optical parts.
  • the anti-reflecting membranes used for the present optical parts are formed by vapor deposition, and hence a vacuum process is needed.
  • the anti-reflecting membranes include multi-layer type and single-layer type, and the single-layer type is preferred because the multi-layer type is superior in anti-reflecting performance, but requires many production steps.
  • Materials used for optical parts such as lens include transparent materials such as glass (refractive index: 1.5-1.54), acrylic resins (refractive index: 1.49), PET resins (polyethylene terephthalate resins) (refractive index: 1.56), etc.
  • refractive index of these materials is shown by n 1 and that of air is shown by no, reflectance R is represented by the following formula.
  • R n 1 - n 0 / ( n 1 + n 0 ) 2
  • the reflectance at one side of the transparent parts is 3.9-4.0% for glass, 3.9% for acrylic resin and 4.8% for PET resin.
  • the refractive index of the anti-reflecting membrane to be applied to glass is suitably about 1.22.
  • even fluorinated resins which are known to be relatively low in refractive index have a refractive index of about 1.34 and even magnesium fluoride which is known to be particularly low in refractive index among inorganic materials has a refractive index of about 1.38, and thus it is very difficult to obtain sufficient anti-reflecting performance with single-layer membranes.
  • the aerogel thin membrane is a thin membrane comprising fine particles having pores inside (fine hollow particles) and a binder holding the fine hollow particles.
  • the pores in the aerogel thin membrane have a refractive index substantially the same as that of air (refractive index: 1.0), and consequently the membrane has a refractive index near that of air even when the refractive index of the material of the fine hollow particles or the binder holding the fine hollow particles is high.
  • the reflectance can be reduced by forming the membrane on a plate.
  • Another method for lowering the refractive index of single-layer membrane, being different from the method of using the aerogel, is to use a membrane of low refractive index disclosed in JP-A-7-92305 . It is disclosed that the surface of superfine organic particles is exposed on the side near to air, and irregularities are formed on the surface, thereby reducing the surface density, and, as a result, a membrane of low refractive index is formed.
  • another method comprises use of membrane of low refractive index having pores in the form of a honeycomb as disclosed in JP-A-2004-83307 .
  • a plurality of pores in the form of a honeycomb structure are formed so that they pass through fine silica particles and are parallel to each other, whereby maximum pore content can be obtained without reducing the strength of fine silica particles per se. It is disclosed that according to this method, low refractive index membranes excellent in mechanical strength can be formed.
  • the present multi-layer anti-reflecting membranes prepared using magnesium fluoride, etc. are low in adhesion to a lens having a convex surface or concave surface, and sometimes peel off during long term use. This tendency is conspicuous especially when the material of the membranes is an acrylic resin.
  • the aerogel thin membrane disclosed in JP-A-2003-201443 has the problem of reduction in mechanical strength due to high pore content.
  • the physical strength of membranes depends greatly upon the physical strength of the fine hollow particles.
  • Aerogel thin membranes in which the thickness of shell of the fine hollow particles is thin are difficult to increase the physical strength.
  • the pore is made larger by increasing the thickness of shell of the fine hollow particles, the size of particles increases and the membrane tends to scatter visible light, resulting in reduction of transmittance, which is practically unacceptable.
  • Further problem is in the specialty of production process which uses carbon oxide of supercritical state. Particularly, for optical parts such as a lens which is not flat, but has irregularities, it is essential to consider the technology of membrane production.
  • the low refractive index membrane disclosed in JP-A-7-92305 and the low refractive index membrane having pores in the form of honeycomb structure disclosed in JP-A-2004-83307 are considered to have high mechanical strength due to crosslinking or polymerization, but there is the possibility of increase of refractive index owing to incorporation of dusts in the irregularities of the membrane surface.
  • the refractive index is about 1.3-1.4, which is disparate from the ideal value (lower than 1.3).
  • the object of the present invention is to solve the above problems. That is, the object is to provide an optical part having an anti-reflecting membrane which has both the high anti-reflecting performance and the high physical strength, and a display apparatus using the same.
  • the present invention discloses also an optical part having anti-reflecting membrane further imparted with mildew proofing function, and a display apparatus using the same.
  • the above membrane has a refractive index smaller that that of the binder and is excellent in physical strength because of using inorganic oxide particles having no pores although the membrane has pores inside, and further is high in adhesion to the transparent materials such as acrylic resins and glasses, and it has been found that optical parts such as lens which have the above membrane are less in reflection at the surface and high in light transmission, and besides high in physical strength since they are superior in adhesion to the surface of the membrane.
  • the pores in the membrane are not present uniformly, but are localized in the vicinity of the surface of the anti-reflecting membrane rather than in the vicinity of the surface of the plate, and hence even if there are some differences in thickness of the membrane, the anti-reflecting function is exhibited and this function is obtained for light of a wide wavelength region.
  • the membrane in which fine silicon dioxide particles are used as the fine inorganic oxide particles and a silicon compound having a hydrolysable residue (silica sol) is used as the binder shows a refractive index considerably smaller than that of silicon dioxide as the binder (the refractive index is specifically 1.33 or smaller) and is excellent in physical strength although it has pores inside.
  • this membrane is also high in adhesion to the plate.
  • the material is a resin such as an acrylic resin
  • the membrane is conspicuously higher in the adhesion as compared with the conventional anti-reflecting membranes comprising magnesium fluoride, fluorinated resins, or the like.
  • this membrane has a very small surface resistance, there is exhibited an effect that dusts such as dirt hardly adhere to the membrane even under low temperature conditions such as winter.
  • the present invention has an additional object to impart mildew proofing function to the anti-reflecting membrane formed on the optical parts such as lenses and prisms.
  • Means for attaining the above objects are as follows.
  • FIG. 1 shows some examples of the optical parts according to the present embodiments.
  • Anti-reflecting membrane 1 is provided on the surface of the respective optical parts.
  • the anti-reflecting membranes are provided on both the light receiving face of incident light 2 and the light outgoing face of outgoing light 3.
  • the anti-reflecting membrane is provided only on the light outgoing face because the reflectance of the mirror face 4 which is a light receiving face of incident light must be enhanced.
  • the lens in FIG. 1 is a convex lens, and the fixing portion 5 to optical system is shown at an end of the lens.
  • the anti-reflecting membrane provided on the surface of the optical parts according to this embodiment is formed of inorganic oxide particles and a binder.
  • the binder functions as a binder of the anti-reflecting membrane.
  • this membrane is formed by coating a paint comprising a mixture of at least inorganic oxide particles, a binder and a solvent on a substrate plate and heating the coat.
  • the binder is a thermosetting compound such as silica sol, epoxy resin monomer or melamine resin monomer
  • a catalyst for acceleration of polymerization namely, thermosetting of the coat
  • the anti-reflecting membrane according to this embodiment can be formed by single-layer process, but may be formed by multi-layer process.
  • paint 7 is coated on a substrate plate 6 to form a coat, followed by rapidly heating the coat.
  • the solvent is rapidly vaporized in the coat to produce bubbles 8 in the coat.
  • the bubble portions are maintained as pores 9 to form the anti-reflecting membrane 1 according to this embodiment.
  • FIG. 3 is a photograph showing a section of one example of the anti-reflecting membrane according to this embodiment, in which the anti-reflecting membrane is formed on an acrylic substrate plate.
  • the inorganic oxide is particle of silicon dioxide, and silica sol is used as the binder.
  • a low refractive index membrane is formed on the acrylic plate, and furthermore carbon is formed on the membrane.
  • the carbon is formed only for avoiding rupture of the section in preparation of a sample of the section for measurement, and it does not affect the effect of the anti-reflecting membrane according to this embodiment.
  • the shape of the pores is indeterminate, and as for the size thereof, length of the major axis is 5-150 nm.
  • the major axis here means an axis which can be taken at the longest distance in the pore, and the length of the major axis is the above distance.
  • the refractive index can be controlled by changing the proportions of silicon dioxide (refractive index: about 1.5) which is a binder of the membrane and pores (refractive index: about 1.0) in the membrane. Specifically, the greater the proportion of the pores, the smaller the refractive index.
  • the formation of the pores can also be controlled by the boiling point of the solvent and the thermosetting temperature after coating the paint on the substrate plate.
  • a greater number of pores are formed in relatively upper part of the membrane (in the vicinity of the outermost surface) as is shown in FIG. 3. It is considered that this is because bubbles which begin to be formed in the paint rise to the vicinity of the surface by thermosetting, namely, by heating. That is, this means that the refractive index tends to lower gradually from the plate side, and even in the case of one layer, there is a gradient of refractive index in the layer. As a result, it is meant that the plate side has a refractive index closer to that of the plate and the surface side which is not the plate side has a refractive index closer to that of air. Thus, reflection at the interface of the plate and the anti-reflecting membrane and reflection at the interface of air and the anti-reflecting membrane can be reduced with one layer.
  • a method of using a plurality of layers can be considered. According to this method, the pores are formed not only in the vicinity of the surface, but also in the inside part, and hence the physical strength of the membrane is further improved.
  • the membrane is excellent also in rub resistance because many pores are present inside the membrane, and less pores are present in the surface of the membrane. If the pores are present in a greater number in the vicinity of the surface, the irregularities on the surface of the membrane become greater, and thus when the surface is wiped with a fabric, the fabric is apt to be caught by the irregularities, while if the irregularities are small, the fabric is hardly caught by the irregularities. Therefore, the membrane is hardly peeled off or damaged.
  • the binder mention may be made of highly transparent organic or inorganic polymer materials and polymerizable materials.
  • the lens substrate being a resin
  • the inorganic materials tend to have a higher hardness, and hence are suitable.
  • materials of low refractive index are suitably silicon-based materials.
  • the organic polymer materials include thermoplastic polymer materials. Examples thereof are acrylic resins, polystyrenes, styrene-acryl copolymers, polyester resins, polyvinyl chloride, ethylene-vinyl acetate copolymers, polyethylene terephthalate resins, polyvinylidene chloride resins, polycarbonate resins, etc.
  • the organic polymerizable materials include thermosetting polymer materials. Examples thereof are polyamic acid derivatives having aliphatic skeleton and the like.
  • the inorganic polymer materials include, for example, silicon compounds having a hydrolysable residue (general name: silica sol) and titanium compounds having a hydrolysable residue (general name: titania sol). These are compounds formed by polymerization of alkoxysilane or alkoxytitanium to a molecular weight of about several thousand, and are in the state of being soluble in an alcoholic solvent. A binder of silicon dioxide or titanium oxide can be formed by heating the above compound.
  • the inorganic polymerizable materials include, for example, alkoxysilanes having various substituents such as amino group, chloro group and mercapto group. Specific examples thereof will be shown in the explanation of silicon compounds having a hydrolysable residue given hereinafter.
  • silicon-based materials are suitable as binders.
  • silicon compounds having a hydrolysable residue are suitable. They will be explained in detail below.
  • silica sol As one of silicon compounds having a hydrolysable residue, mention may be made of silica sol. This is a material which converts to silicon dioxide by heating. This is suitable for anti-reflecting membranes used in display apparatus since the resulting silicon dioxide is high in light transmission. Furthermore, fine silicon dioxide particles can be more easily dispersed in the membrane than acrylic resins or polycarbonate resins. If the fine silicon dioxide particles cannot be dispersed in the membrane, namely, if they agglomerate, the membrane becomes cloudy to cause scattering of incident light, resulting in decrease of light transmittance, which is not preferred.
  • a general method for preparation of silica sol is as follows.
  • alkoxy group When tetraalkoxysilane is heated under the weakly acidic condition, alkoxy group is hydrolyzed to hydroxyl group, which reacts with alkoxysilane group present nearby to increase in molecular weight with forming silicon-oxygen-silicon bond.
  • the average molecular weight is generally several thousand. If the average molecular weight is too low (in the case of several hundred), there is a problem that a part of it is volatilized in forming silicon dioxide membrane by the subsequent heating. If the average molecular weight is too high (in the case of more than several ten thousand), it becomes insoluble in the solvent used, and hence precipitates in preparation of a paint.
  • the tetraalkoxysilanes used in preparation of silica sol include, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetraisobutoxysilane, tetrabutoxysilane, etc.
  • Other examples are silicon compounds having chlorine group in place of alkoxysilane group, for example, silicon tetrachloride, etc.
  • Silicon compounds having a hydrolysable residue other than silica sol include, for example, those which have amino group, chloro group, mercapto group in addition to tetraalkoxysilanes.
  • the inorganic oxide particles include colorless or white particles of silicon dioxide, aluminum oxide, titanium oxide, cerium oxide, etc. With reference to the size of the particles, it is preferred that the minor axis of the particles is less than the average thickness of the membrane for improving flatness of the membrane. Furthermore, among the above compounds, silicon dioxide (refractive index: about 1.5-1.7) and aluminum oxide (refractive index: about 1.7-1.9) which have relatively low refractive index are suitable because membranes of low refractive index can be obtained more easily. Therefore, explanation will be made of especially the silicon dioxide particles.
  • the particle diameter is preferably 1/2 or less of wavelength so that the light entering in the membrane is not scattered. Since the wavelength region of visible light is 380-780 nm, the particle diameter is preferably 190 nm or less so that the light is not scattered in this region.
  • the average particle diameter is preferably 190 nm or less so that the visible light entering in the membrane (wavelength: 380-760 nm) is not scattered.
  • the average particle diameter is more than 190 nm, the entering light is scattered and the membrane appears cloudy, and thus the membrane becomes difficult to be applied to display apparatuses.
  • the thickness is also preferably 190 nm or less for the same reasons as above. With decrease of the particle diameter of the silicon dioxide particles, the transparency is improved. Therefore, the average particle diameter is preferably 100 nm or less.
  • the minor axis is preferably 100 nm or less so that decrease of light transmittance is inhibited, and 40 nm or less so that decrease of the transmittance is less than 1%.
  • a dispersant is added.
  • a nonionic dispersant is suitable. A part of ionic dispersants sometimes accelerate polymerization of the silicon compound having a hydrolysable residue, and viscosity of the paint much increases before coating on the substrate plate and in some cases the paint becomes gelling or is hardened to a complete solid.
  • the paint cannot be coated, and it is desired to confirm whether the above phenomena occur or not before use.
  • a dispersant is used, the strength of the membrane tends to decrease, and hence it is desirable not to use the dispersant or to use it in an amount as small as possible.
  • the silicon dioxide particles suitable is colloidal silica in which the particles are previously dispersed.
  • the particles in the colloidal silica have many hydroxyl groups on the surface and hence are high in hydrophilicity.
  • the anti-reflecting membrane formed using the colloidal silica is hydrophilic and simultaneously very low in resistance. Specifically, it is about 1 ⁇ 10 10 - 10 ⁇ 10 10 ⁇ . This value is very small, namely, 1/10,000 to 1/1,000,000 of the resistance of glass, acrylic resins, polycarbonate resins, PET resins, etc. Therefore, dusts such as dirt hardly adhere to the membrane. Therefore, in a greenhouse where the membrane of the present invention is provided on the transparent faces, the volume of light entering therein increases to result in shortening of growing period of plants.
  • the compounds having alkoxysilane group can be bonded to the above substrate plate in a larger amount than to conventional glass plates, etc. Therefore, liquid repellants such as perfluoro polyether compounds or perfluoroalkyl compounds having alkoxysilane group mentioned hereinafter can be bonded to the above substrate plates in a larger amount than to substrate plates such as conventional glass plates.
  • the plate can be improved in liquid repellency as compared with the conventional glass plates.
  • the substrate plate can be treated with liquid repellants such as perfluoro polyether compounds or perfluoroalkyl compounds having alkoxysilane group mentioned hereinafter to impart liquid repellency to the plate.
  • silicon dioxide particles suitable as a constituting material of the anti-reflecting membrane have indeterminate form.
  • the silicon dioxide particles of indeterminate form more easily lower the refractive index of the formed membrane as compared with those of true sphere.
  • the binder of membrane which is so-called support material is silica sol, and silicon dioxide is very low in function as a support material of the membrane. Therefore, without silica sol, it is difficult to maintain the shape as a membrane, and the membrane becomes powders. Therefore, in order to increase the physical strength of the membrane, the smaller proportion of silicon dioxide in the membrane is suitable.
  • a membrane of lower refractive index can be formed by using silicon dioxide in the form of chain than using spherical silicon dioxide, it is supposed that in the membrane the silicon dioxide in the form of chain can more easily form pores as compared with the spherical silicon dioxide.
  • aluminum oxide has small refractive index and is suitable, and alumina sol having many hydroxyl groups on the surface forms a membrane of low resistivity and is suitable.
  • solvents for paint those which can dissolve or uniformly disperse the binder are effective.
  • Alcohol solvents are suitable when the paint contains the silicon compound having hydrolysable residue suitable as the binder and the silicon dioxide particles suitable as the inorganic oxide particles.
  • the alcohol solvents are ethanol, n-propanol, isopropanol, n-butanol, iso-butanol, tert-butanol, n-pentanol, iso-pentanol, tert-pentanol, etc.
  • the alcohol solvents are suitable because they hardly swell, deform or dissolve the substrate plate formed of polycarbonate resin, acrylic resin, etc. Furthermore, the alcohol solvents having many carbon atoms tend to be high in boiling point. Moreover, with increase of the number of branched-parts, the boiling point tends to decrease. In preparation of membrane mentioned hereinafter, a membrane of low refractive index can be more easily prepared when the boiling point is somewhat lower than the thermosetting temperature. This is because the volume of pores produced with vaporization of the solvent in the membrane increases.
  • the inorganic oxide particles agglomerate, they scatter the incoming light. Therefore, there are problems that the transmittance lowers or the membrane becomes cloudy. Especially, this tendency is conspicuous when the diameter of the inorganic oxide particles is 60 nm or more. This is because even when a small number of particles agglomerate, the major axis of the agglomerate is 100 nm or more to hinder transmission of light in the visible region. Therefore, it becomes possible to inhibit the agglomeration of the particles by adding a dispersant.
  • the amount of the dispersant added is about 0.1-5% by weight based on the solid content of the anti-reflecting membrane, and is suitably controlled depending on the proportion of the particles or the like.
  • Nonionic and ionic surfactants are effective as the dispersant.
  • the anti-reflecting membranes containing these compounds are colorless even by visual inspection. Since the portion exhibiting the mildew proofing function is the portion of the quaternary salt structure of nitrogen in the pyridine ring, the mildew proofing function tends to be enhanced with decrease of n when the compounds are added at the same weight ratio.
  • X is also a halogen atom, specifically, chlorine, bromine or iodine.
  • Nitrogen in the bipyridyl ring has also a quaternary salt structure, and since this portion is hydrophilic, water-solubility and water-absorbability is lowered with increase of hydrophobic portion, namely, the portion of alkyl chain.
  • the proportion of nitrogen in the molecule is preferably smaller. Specifically, the proportion of nitrogen in the compound is preferably less than 6% by weight.
  • n is preferably 10 or more
  • n is preferably 9 or more
  • X being iodine n is preferably 7 or more.
  • the anti-reflecting membranes containing these compounds are colorless even by visual inspection. Since the portion exhibiting the mildew proofing function is the portion of the quaternary salt structure of nitrogen in the bipyridyl ring, the mildew proofing function tends to enhance with decrease of n when the compounds are added at the same weight ratio. Furthermore, as compared with the compounds having dipyridinium salt structure, they have higher mildew proofing function, and hence they exhibit high mildew proofing function even with addition in a slight amount.
  • the anti-reflecting membranes containing the structure are colorless even by visual inspection.
  • the exhibition of the mildew proofing function is supposed to be synergistic effect of the carbamate structure and chlorine, bromine or iodine atom.
  • the organic compounds having benzimidazole structure and the organic compounds having carbamate structure have a tendency not to change much in anti-reflecting performance (specifically a tendency to show substantially no change in refractive index of the membrane) even when the amount of the compound added to the membrane is larger, and in this respect, these compounds are suitable for the optical parts and image display apparatuses of the present invention.
  • the membrane of low refractive index according to this embodiment is formed by pretreatment of substrate plate, coating and heating. It can be formed by single-layer process, but may also be formed by multi-layer process. Furthermore, for improving rub resistance, a post-treatment after heating can be carried out. Details of the treatments will be explained.
  • Solvents or cleaning agents which can sufficiently dissolve or remove the dirt adhering to the substrate plate are used for the cleaning of the substrate plate.
  • the substrate plate being a resin such as an acrylic resin or polycarbonate resin
  • alcohol solvents such as methanol, ethanol, propanol and butanol are used rather than those solvents which cause generation of cloudiness owing to dissolution of the surface (such as tetrahydrofuran, dioxane, etc.).
  • the substrate plate being glass, the dirt can be removed together by thinly etching the surface by dipping in a basic solution (e.g., aqueous sodium hydroxide solution).
  • the thickness is less in variation to provide good optical characteristics. Furthermore, since adhesion between the substrate plate and the membrane is improved, the membrane strength is improved.
  • a method of surface modification using apparatuses such as plasma irradiators and a method of chemical modification of the surface with an acidic or basic solution, or the like.
  • the method includes, for example, oxygen plasma irradiation, exposure to an ozone atmosphere, and UV irradiation.
  • active oxygen acts on the surface of the substrate plate to produce hydroxyl groups, carboxyl groups or the like. Since these groups are hydrophilic, the surface on which they are produced is improved in wettability. Therefore, a membrane of uniform thickness can be easily obtained by coating the paint.
  • UV irradiation oxygen in the air is changed to oxygen in active state, which modifies the surface, and hence the UV irradiation results in the similar effects to those of oxygen plasma irradiation and exposure to ozone atmosphere.
  • Other methods include argon plasma irradiation. The wettability is also improved by argon plasma irradiation. However, in case the output of high frequency electric source of plasma generation apparatus is the same, the argon irradiation requires a longer irradiation time than the oxygen plasma.
  • spin coating, dip coating, bar coating, coating by applicator, spray coating, flow coating, etc. can be employed, and the coating method is not particularly limited.
  • the coating method is not particularly limited.
  • spin coating the number of revolution and time of revolution affect the thickness of membrane. Particularly, the number of revolution greatly affect the thickness, and the larger number of revolution gives the thinner membrane.
  • dip coating the dipping time and take-up speed affect the thickness of membrane. Particularly, the take-up time greatly affects the thickness, the lower take-up speed tends to result in decrease of thickness.
  • Depth of the groove on the surface of the bar in the case of bar coating, size of gap in the case of coating by applicator, moving speed of spray in the case of spray coating, and angle in holding the substrate plate, and amount of paint used in the case of flow coating are the respective coating conditions.
  • the objective thickness in coating is desirably 60-190 nm.
  • the thickness of the membrane of the present invention is suitably 60-190 nm.
  • Luminosity factor varies between individuals.
  • a wavelength ( ⁇ ) at which relative spectral responsivity attains a maximum in the photopic relative luminosity curve (" Industrial Science of Color", Yoshinobu Naya, 2nd edition, published by Asakura Shoten, February 10, 1984, pages 4 to 80 ) is around 555 nm.
  • a wavelength at which men's luminosity factor attain a maximum is around 555 nm in a bright atmosphere.
  • the refractive index of an anti-reflecting membrane at which the reflectance can be theoretically reduced to 0% determines depending on the refractive index of the substrate plate used, and a square root of the refractive index of the substrate plate is the refractive index of the anti-reflecting membrane.
  • the substrate plates used in image display apparatuses such as monitors there may be used glass, acrylic resin, PET resin, or the like, and it is desired that an anti-reflecting membrane of 1.22-1.24 in refractive index is used in the case of glass of 1.50-1.54 in refractive index, an anti-reflecting membrane of 1.22 in refractive index is used in the case of acrylic resin of 1.49 in refractive index, and an anti-reflecting membrane of 1.25 in refractive index is used in the case of PET resin of 1.56 in refractive index.
  • the thickness of the anti-reflecting membrane which can theoretically reduce the reflectance of the substrate plate having a refractive index of 1.5 in a wavelength of 555 nm is 116 nm. Since the reflectance of one side of the substrate plate having no anti-reflecting membrane is about 4%, the thickness of the anti-reflecting membrane which can reduce the reflectance to 4% or less is in the range of 90 nm to 140 nm.
  • heating is carried out for volatilizing the solvent or allowing the polymerization to proceed for some binder.
  • the heating temperature is higher than the boiling point of the solvent, bubbles are generated in the membrane and remain finally as pores to lower the refractive index of the membrane.
  • the heating temperature must be lower than the heat resisting temperature of the substrate plate in addition to the boiling point of the solvent, and, furthermore, when a thermosetting material is used as the binder, the heating temperature must be higher than the thermosetting temperature. Therefore, it is necessary to select the solvent, the substrate plate and the binder so as to satisfy the above requirements. Furthermore, if there is difference in volumetric shrinkage of the membrane and the substrate plate in cooling after the heating, there may occur peeling of the membrane and deformation of the substrate plate, and hence it is desired to select the substrate plate and membrane which comprise similar materials or have similar linear expansion coefficient. From this viewpoint, when silica sol suitable as a binder and silicon dioxide particles suitable as the inorganic oxide particles are used, the membrane formed by heating becomes silicon dioxide, and, hence, glass or quartz which is similar to silicon dioxide in linear expansion coefficient is suitable as the substrate plate.
  • the anti-reflecting membrane of the present invention is formed by thermal cure, and the fouling resistance of the surface is improved by forming a layer comprising a fluorine compound having liquid repellency.
  • the layer comprising a fluorine compound having liquid repellency must be very thin so that the anti-reflecting effect of the anti-reflecting membrane formed is not deteriorated.
  • the influence on the reflectance can be avoided by reducing the thickness of the layer to less than 56 nm as mentioned in the above (2-2).
  • the thickness of the liquid repellent layer at which the influence on the reflectance is less than 1% is less than 6 nm according to our research in the wavelength of 555 nm for which men's luminosity factor is high.
  • Formation of the layer comprising a fluorine compound having liquid repellency is carried out in the following two manners.
  • a perfluoro polyether compound or perfluoroalkyl compound having alkoxysilane group at the end is effective as the liquid repellant.
  • Examples of the liquid repellants and method for formation of liquid repellent layer will be shown below.
  • the following compounds 1-12 can be mentioned as the perfluoro polyether compound or perfluoroalkyl compound having alkoxysilane group at the end.
  • compounds 1-8 are obtained by the following synthesis methods.
  • Compounds 9-12 are commercially available from Hydrus Chemical Co. as 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and 1H,1H,2H,2H-perfluorodecyltriethoxysilane.
  • Other commercially available compound is Daikin Industries' OPTOOL DSX.
  • fluorine chain is perfluoro polyether
  • the liquid repellent coating layers formed by the compounds having this fluorine chain have the feature that they show substantially no decrease of water repellency (decrease of less than 5°) even they contact with oil or cigarette smoke in addition to water over a long period of time (1000 hours).
  • These compounds are represented by the following formulas. [F ⁇ CF(CF 3 )-CF 2 O ⁇ n -CF(CF 3 )]-X-Si(OR) 3 ⁇ F(CF 2 CF 2 CF 2 O) n ⁇ -X-Si(OR) 3
  • X is a bonding portion of perfluoro polyether chain and alkoxysilane residue
  • R is an alkyl group
  • Dupont's Krytox 157FS-L (average molecular weight: 2500) (25 parts by weight) was dissolved in 3M's PF-5080 (100 parts by weight), and thionyl chloride (20 parts by weight) was added to the solution, followed by refluxing for 48 hours with stirring.
  • Thionyl chloride and PF-5080 were volatilized by an evaporator to obtain an acid chloride of Krytox 157FS-L (25 parts by weight).
  • PF-5080 100 parts by weight
  • Chisso's Sila-ace S330 (3 parts by weight)
  • triethylamine (3 parts by weight)
  • Compound 3 (30 parts by weight) was obtained in the same manner as in synthesis of the compound 1, except that Daikin Industies' DEMNUM SH (average molecular weight: 3500) (35 parts by weight) was used in place of Dupont's Krytox 157FS-L (average molecular weight: 2500) (25 parts by weight).
  • Compound 4 (30 parts by weight) was obtained in the same manner as in synthesis of the compound 1, except that Chisso's Sila-ace S360 was used in place of Chisso's Sila-ace S330 (3 parts by weight), and Daikin Industies' DEMNUM SH (average molecular weight: 3500) (35 parts by weight) was used in place of Dupont's Krytox 157FS-L (average molecular weight: 2500) (25 parts by weight).
  • Compound 5 (3.5 parts by weight) was obtained in the same manner as in synthesis of the compound 1, except that Daikin Industies' 7H-dodecafluoroheptanoic acid (molecular weight: 346.06) (3.5 parts by weight) was used in place of Dupont's Krytox 157FS-L (average molecular weight: 2500) (25 parts by weight).
  • Compound 8 (4.5 parts by weight) was obtained in the same manner as in synthesis of the compound 1, except that Daikin Industies' 9H-hexadecafluorononanoic acid (molecular weight: 446.07) (4.5 parts by weight) was used in place of Dupont's Krytox 157FS-L (average molecular weight: 200) (25 parts by weight) and Chisso's Sila-ace S320 (2 parts by weight) was used in place of Chisso's Sila-ace S310 (2 parts by weight).
  • FIG. 5 schematically shows an optical system of a front projector type display apparatus.
  • a white light generated from a lamp 11 is collected by a reflector 12 and is emitted to a first lens array 14 through a concave lens 13.
  • the first lens array divides the incoming beam to a plurality of beams and leads the beams to efficiently pass through a second lens array 15 and a polarization converter 16.
  • the constituting respective lens cells project the images of lens cells of the first lens array to the side of display devices 17, 18 and 19 corresponding to the three primary colors of red, green and blue (RGB).
  • RGB red, green and blue
  • mirrors 26-29 are also provided for changing the direction of light in the optical system.
  • the white light generated at the light source is separated to the three primary colors of RGB by dichroic mirrors 30 and 31 and irradiated to the corresponding display devices 17, 18 and 19.
  • the images on the display devices 17, 18 and 19 are subjected to color synthesis by a dichroic-cross-prism 32 and are further projected on a screen 34 by a projection lens 33, thereby to form a large plane image.
  • the first relay lens and the second relay lens are for compensation of the longer light path of the display device 19 as compared with the light path of the display devices 17 and 18 from the light source.
  • the condenser lenses 21, 22 and 23 are for inhibiting expansion of light which has passed through the display devices 17, 18 and 19 in order to attain efficient projection by the projection lens.
  • the outputted light passes through a light emitting tube
  • various lenses such as condenser and relay lenses, lens arrays, a polarization converter, display devices and dichroic-cross-prism
  • reflection at the surface of them can be reduced and light transmission can be improved by providing anti-reflecting membranes on the surfaces through which light passes, namely, both of the light receiving face and the light outgoing face.
  • the reflection at the light transmitting surface of the dichroic mirrors can be reduced by providing the anti-reflecting membrane and light transmission is improved.
  • FIG. 6 schematically shows the optical system of the display apparatus of rear projection type.
  • an optical unit 36 portion of the optical system of FIG. 5 from which the screen is omitted
  • a rear mirror 37 The light leaving the optical unit is changed in its direction at the rear mirror and then projected on a screen 38. Thus, an image is displayed on the screen.
  • the incident light 41 leaving the optical unit is separated to image light 42 and reflected light 43 at the glass surface and projected on the screen as shown in FIG. 7, and hence there is a problem that the image is seen double and consequently the minuteness is reduced.
  • the anti-reflecting membrane of this embodiment can be formed on the transparent substrates such as of glass, polycarbonate resin and acrylic resin.
  • the present invention is effective for the uses in which it is desired to efficiently utilize the sunlight without reflecting it.
  • the parts which transmit light such as lens and optical filter used in various optical apparatuses. These uses include liquid crystal projector, microscope, telescope, camera, and image recording apparatuses using video and DVD. Additional uses are application to transparent walls of greenhouses for stable and rapid growth of plants, etc. Another uses are application to transparent walls of water tank for observation and enjoying animals and plants, insects, fishes, and the like for inhibiting reflection of ambient objects on the walls and improving visibility.
  • the present invention can be applied to display apparatuses such as liquid crystal displays, plasma displays, electroluminescent (organic EL) displays which are used for televisions, portable telephones, navigator systems, display of speed and revolution number of vehicles. Specifically, it is suitable to form the anti-reflecting membrane on the outermost surface of display parts of these display apparatuses.
  • the anti-reflecting membrane can be formed on the surface of panels of solar batteries for improving efficiency of electricity generation with sunlight. It is also effective to apply the anti-reflecting membrane to the outermost surface of optical storage media since laser beams in addition to sunlight can be efficiently entered.
  • the membrane can improve light transmission and visibility even in winter of low humidity or in environment including dusts in a large amount since it is low in resistance, and dusts hardly adhere thereto.
  • fouling resistance is improved by imparting liquid repellency, and as a result, light transmission and visibility are improved. Since the membrane of the present invention has these features, the transparent substrate plates having the membrane are also effective as interior building materials such as walls or partitions of clean room.
  • optical parts having anti-reflecting membrane which is of low resistance, high adhesion and low refractive index there can be obtained optical parts having anti-reflecting membrane which is of low resistance, high adhesion and low refractive index, and by using the optical parts, it becomes possible to obtain display apparatuses of high performance.
  • the optical parts have the feature that the anti-reflecting membrane hardly gets mildewed on the surface even in the environment of high temperature and high humidity.
  • transmittance for light of 550 nm was measured.
  • the transmittance of the lens provided with the anti-reflecting membrane was 99%.
  • the transmittance of a lens made of an acrylic resin and provided with no anti-reflecting membrane was about 92%, and thus it was confirmed that the membrane had a function to improve the light transmittance.
  • the section of the formed anti-reflecting membrane was observed by TEM to confirm presence of pores of 5-150 nm in size as shown in FIG. 3. Furthermore, according observation of the section of the membrane, the number of pores was less on the substrate plate side, and the proportion of the pores increased gradually with closing to the surface side. Thus, there was obtained a membrane having a refractive index close to that of the material of the membrane on the substrate plate side and a refractive index close to that of air on the surface side. It is supposed that the reflection at the respective interfaces can be inhibited by reducing the difference of refractive index at the respective interfaces.
  • the distribution of the pores in the membrane in the following examples was the same as above.
  • the surface resistivity of the lens having the anti-reflecting membrane was measured to obtain 1 ⁇ 10 10 ⁇ under the conditions of a temperature of 20°C and a humidity of 50%. The measurement was conducted in accordance with ASTM D-257.
  • the surface resistivity of the lens having no anti-reflecting membrane was higher than 1 ⁇ 10 16 ⁇ . Therefore, the lens having the anti-reflecting membrane was hardly electrostatically charged as compared with the lens having no anti-reflecting membrane, and substantially no dusts adhered to the former lens.
  • a lens having an anti-reflecting membrane formed thereon was formed in the same manners as in (1)-(5) of Example 1, except that the lens made of acrylic resin was changed to a lens made of glass and having the same size as in Example 1.
  • Example 2 The same evaluation as of (6) in Example 1 was conducted to obtain a thickness and a refractive index of 120 nm and 1.25, respectively.
  • the reflectance at 550 nm was 0.5%.
  • the reflectance of a lens having no anti-reflecting membrane was about 8%, and thus it was confirmed that the membrane had an anti-reflecting function.
  • transmittance for light of 550 nm was measured.
  • the transmittance of the lens having the anti-reflecting membrane was 99%.
  • the transmittance of a lens made of an acrylic resin and having no anti-reflecting membrane was about 92%, and thus it was confirmed that the membrane had a function to improve the light transmittance.
  • the surface resistivity of the lens having the anti-reflecting membrane was measured to obtain 1 ⁇ 10 10 ⁇ under the conditions of a temperature of 20°C and a humidity of 50%.
  • the surface resistivity of the lens having no anti-reflecting membrane was 1 ⁇ 10 12 ⁇ . Therefore, the lens having the anti-reflecting membrane was not easily electrostatically charged as compared with the lens having no anti-reflecting membrane to cause substantially no adhesion of dusts.
  • a lens having an anti-reflecting membrane was formed in the same manners as in (1)-(5) of Example 1, except that the material of the anti-reflecting membrane was changed to magnesium fluoride and formation of the membrane was carried out by vapor deposition, not by coating.
  • Example 1 The same evaluation as of (6) in Example 1 was conducted to obtain a thickness and a refractive index of 120 nm and 1.38, respectively.
  • the reflectance at 550 nm was 3%.
  • the reflectance of a lens made of an acrylic resin and having no anti-reflecting membrane was about 8%, and thus it was confirmed that the membrane had an anti-reflecting function, but this anti-reflecting function was lower than that in Example 1.
  • transmittance for light of 550 nm was measured.
  • the transmittance of the lens having the anti-reflecting membrane was 96%.
  • the transmittance of a lens made of an acrylic resin and having no anti-reflecting membrane was about 92%, and thus it was confirmed that the membrane had a function to improve the light transmittance, but this function was lower than that in Example 1.
  • the surface resistivity of the lens having the anti-reflecting membrane was measured to obtain 2 ⁇ 10 14 ⁇ under the conditions of a temperature of 20°C and a humidity of 50%. Therefore, the lens was more easily electrostatically charged as compared with the lens formed in Example 1 to cause easy adhesion of dusts.
  • Example 2 In the same manner as in Example 1, the cross cut exfoliation test was carried out to examine adhesion of the anti-reflecting membrane. As a result, peeling of the anti-reflecting membrane was seen in the whole area to which a tape was applied.
  • the lenses of the present invention were higher in light transmittance, inhibited from adhesion of dusts, and higher in adhesion of the anti-reflecting membrane as compared with lenses provided with conventional anti-reflecting membrane made of magnesium fluoride.
  • a lens having an anti-reflecting membrane was formed in the same manners as in Example 2, except that the material of the anti-reflecting membrane was changed to magnesium fluoride and formation of the membrane was carried out by vapor deposition, not by coating.
  • Example 2 The same evaluation as of (6) in Example 1 was conducted to obtain a thickness and a refractive index of 120 nm and 1.38, respectively.
  • the reflectance at 550 nm was 3%.
  • the reflectance of a lens having no anti-reflecting membrane was about 8%, and thus it was confirmed that the membrane had an anti-reflecting function, but this anti-reflecting function was lower than that in Example 2.
  • transmittance for light of 550 nm was measured.
  • the transmittance of the lens having the anti-reflecting membrane was 96%.
  • the transmittance of a lens made of glass and having no anti-reflecting membrane was about 92%, and thus it was confirmed that the membrane had a function to improve the light transmittance, but this function was lower than that in Example 2.
  • the surface resistivity of the lens having the anti-reflecting membrane was measured to obtain 2 ⁇ 10 14 ⁇ under the conditions of a temperature of 20°C and a humidity of 50%. Therefore, the lens was more easily electrostatically charged as compared with the lens formed in Example 2 to cause easy adhesion of dusts.
  • Example 2 In the same manner as in Example 2, the cross cut exfoliation test was carried out to examine adhesion of the anti-reflecting membrane. As a result, the peeling of the anti-reflecting membrane was seen in the part of 50% of the whole membrane.
  • the lenses of the present invention were higher in light transmittance, inhibited from adhesion of dusts, and higher in adhesion of the anti-reflecting membrane as compared with the lenses provided with conventional anti-reflecting membrane made of magnesium fluoride.
  • a polarization converter having anti-reflecting membrane was formed in the same manner as in Example 1, except that the same anti-reflecting membrane as of Example 1 was formed on both the light receiving face and the light outgoing face of a polarization converter in place of the lens.
  • the light transmittance for 550 nm of this polarization converter was improved by about 7% as compared with that of a polarization converter having no anti-reflecting membrane.
  • the light transmittance of this polarization converter was improved by about 3% as compared with that of a polarization converter having the conventional anti-reflecting membranes made of magnesium fluoride.
  • a display device having anti-reflecting membrane was formed in the same manner as in Example 1, except that the same anti-reflecting membrane as of Example 1 was formed on both the light receiving face and the light outgoing face of a display device in place of the lens.
  • the light transmittance for 550 nm of this display device was improved by about 7% as compared with that of a display device having no anti-reflecting membrane.
  • the light transmittance of this display device was improved by about 3% as compared with that of a display device having the conventional anti-reflecting membranes made of magnesium fluoride.
  • a dichroic-cross-prism having anti-reflecting membranes was formed in the same manner as in Example 1, except that the same anti-reflecting membranes as of Example 1 were formed on the four faces in total of the light receiving faces (three faces) and the light outgoing face of a dichroic-cross-prism in place of the lens.
  • the light transmittance for 550 nm of this dichroic-cross-prism was improved by about 7% as compared with that of a dichroic-cross-prism having no anti-reflecting membrane.
  • the light transmittance of this dichroic-cross-prism was improved by about 3% as compared with that of a dichroic-cross-prism having the conventional anti-reflecting membranes made of magnesium fluoride.
  • a dichroic mirror having anti-reflecting membrane was formed in the same manner as in Example 1, except that the same anti-reflecting membrane as of Example 1 was formed on the light outgoing face of a dichroic mirror in place of the lens.
  • the anti-reflecting membrane was not provided on the light receiving face which was a mirror face.
  • the light transmittance for 550 nm of this dichroic mirror was improved by about 7% as compared with that of a dichroic mirror having no anti-reflecting membrane.
  • the light transmittance of this dichroic mirror was improved by about 3% as compared with that of a dichroic mirror having the conventional anti-reflecting membrane made of magnesium fluoride.
  • the optical parts having anti-reflecting membrane which were produced in Examples 1-6 were subjected to a liquid repelling treatment.
  • a liquid repellant solution 0.5 wt% solutions of the compounds 1-12 (solvent: 3M's PF-5080) were prepared. These were used as liquid repellant solutions.
  • the 0.1 wt% PF-5080 solution of the compound 1, the 0.1 wt% PF-5080 solution of the compound 2, ---------, and the 0.1 wt% PF-5080 solution of the compound 12 are referred to as liquid repellant solution [1], liquid repellant solution [2], --------------, and liquid repellant solution [12], respectively.
  • the optical part was taken out and left to stand for 90 minutes in a thermostat chamber the inside of which was heated to 95°C. The optical part was taken out to complete the treatment.
  • (3) Evaluation of liquid repellency The liquid repellency of the surface of the optical parts after subjected to the liquid repelling treatment was evaluated in terms of contact angle with water. The results are shown in Tables 1-6.
  • the contact angle with water of all the anti-reflecting membranes was smaller than 10°.
  • the contact angle of all the membranes became larger by the liquid repelling treatment. Since the refractive index and reflectance did not change before and after the liquid repelling treatment, it was shown that the liquid repelling treatment did not deteriorate the performances relating to optical characteristics.
  • the compounds 1-4 gave larger contact angles, and at the least, the contact angle was 106° in the case of treating the membrane of Example 2 with compound 1 or 2.
  • the contact angle was large, namely, 110° for all the membranes.
  • the large contact angle means that the membrane is excellent in fouling resistance, and hence it is desired that the contact angle is as large as possible.
  • the compounds 1-4 have perfluoro polyether chains, and other compounds have perfluoroalkyl chains or fluoroalkyl chains. Thus, it is shown that membranes superior in liquid repellency can be formed by carrying out the treatment with compounds having perfluoro polyether chains.
  • a lens having anti-reflecting membrane was formed in the same manner as in Example 1, except that the anti-reflecting paint was coated by dip coating, not by spin coating.
  • the resulting lens was evaluated in the same manner as in (6) of Example 1 to obtain the results similar to those in Example 1.
  • the anti-reflecting membrane can also be formed not only by spin coating, but also by dip coating and other coating methods.
  • a lamp having anti-reflecting membrane on the surface was formed in the same manner as in Example 8, except that the paint was dip coated on a lamp in place of the lens. It was confirmed that this lamp was improved by about 3% in intensity of light at 550 nm as compared with a lamp having no anti-reflecting membrane.
  • Display apparatuses having the optical system shown in FIG. 5 were made using the optical parts formed in Examples 1-6 and 9, and images were displayed. There were obtained images improved about 1.5 time in brightness as compared with those displayed by a display apparatus made using the optical parts having conventional anti-reflecting membrane made of magnesium fluoride. It is considered that this is because the effect of the anti-reflecting membrane to improve light transmittance was exhibited.
  • Compounds 13-19 are compounds having a pyridinium salt structure.
  • Compounds 20 and 21 are compounds having a dipyridinium salt structure.
  • Compound 22 is a compound having a pyridine-N-oxide structure.
  • Compound 23 is a compound having a dipyridyl-N-oxide structure.
  • Compound 24 is a compound having a benzimidazole structure.
  • Compound 25 is a compound having a thiazole compound.
  • Compound 26 is a compound having an isothiazole structure.
  • Compounds 27-29 are organic compounds having a halogen atom and a carbamate structure.
  • paints for anti-reflecting membrane were prepared by the following method.
  • Anti-reflecting paints containing the mildew proofing agent were prepared by mixing a silica sol solution as a binder (containing 2-propanol as a main solvent and 10% by weight of an alkoxysilane polymer) (2 parts by weight), a 5 wt% dispersion of silicon dioxide having an average length of major axis of about 60 nm as inorganic oxide particles (35 parts by weight), 2-propanol (100 parts by weight), and a 2 wt% 2-propanol solution of the mildew proofing agent (2 parts by weight).
  • 2-propanol was used as the solvent because most of the mildew proofing agents only partially dissolve in water.
  • Example 1 the same lens of acrylic resin as used in Example 1 as one of the optical parts of the present invention was cleaned in the same manner as in Example 1, and thereafter the lens was coated with the anti-reflecting paint containing the mildew proofing agent in place of the anti-reflecting paint used in Example 1, followed by heating the coat.
  • the anti-reflecting paint was also coated on the back surface of the lens as in Example 1.
  • a lens having an anti-reflecting membrane containing the mildew proofing agent was produced.
  • Reflectance of the resulting lenses having the anti-reflecting membrane containing the mildew proofing agent was measured.
  • the measurement wavelength was 550 nm.
  • the reflectance of these lenses was 0.5-0.6%.
  • the reflectance of the acrylic resin lenses having no anti-reflecting membrane was about 8%, and it was confirmed that the membranes containing the mildew proofing agents of the present invention also had anti-reflecting function.
  • the light transmittance for 550 nm of these lenses was determined. As a result, the transmittance of these lenses was 99%.
  • the transmittance of the acrylic resin lenses having no anti-reflecting membrane was about 92%, and it was confirmed that the membrane had a function to improve the light transmission.
  • the cross cut exfoliation test was carried out to examine adhesion of the anti-reflecting membrane containing the mildew proofing agent. As a result, no peeling by tape was seen.
  • the white fibrous material was analyzed to find that this was a mildew, while growing of mildews was not seen for the lenses having anti-reflecting membrane containing mildew proofing agent.
  • the lenses having the anti-reflecting membrane containing the mildew proofing agent were dipped in hot water at 40°C for 1 hour and thereafter were left to stand for 1 week in a thermo-hygrostat of 40°C and 95%RH. After lapse of 1 week, it was examined by visual inspection and inspection with a 5x magnifier whether mildews grew or not. The results are shown in Table 8.
  • the proportion of nitrogen in the compounds is suitably less than 6% by weight.

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JP5728572B2 (ja) * 2011-05-17 2015-06-03 キヤノン電子株式会社 光学フィルタ及び光学装置
KR102308494B1 (ko) 2014-04-14 2021-10-01 고쿠리츠다이가쿠호진 토쿄고교 다이가꾸 투명 스크린용 필름 및 그 제조방법과 그것을 구비한 투명 스크린
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CN107109123A (zh) 2014-10-31 2017-08-29 住友化学株式会社 透明被膜
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CN115403972B (zh) * 2022-09-04 2024-03-01 合肥乐凯科技产业有限公司 一种抗光幕布及其制备方法

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